Security enhancing apparatus for attaching to an electronic device

ABSTRACT

An apparatus for attaching to an electronic device, where the electronic device comprises an electrical connector, a back side, a display arranged on a side opposite to the back side, and lateral sides connecting the back side and the side opposite to the back side is disclosed. The apparatus comprises a first body; an electrical connector; a slot for insertion of a smartcard; a fingerprint reader; and circuitry connected to the electrical connector.

TECHNICAL FIELD

The present invention generally relates to an apparatus for attaching toan electronic device, wherein the apparatus is arranged to enhancesecurity for one or more functions of the electronic device by addingbiometric and smart card capabilities.

BACKGROUND

Electronic devices, particularly portable ones such as cellphones, mediaplayers, cameras, portable computers, and any mergers among those, arevery capable in their functions and in their ability to hold and accessdata. Their portability is however a risk in sense of security issues,taking their capabilities into account. A person's or an organisation'sintegrity may swiftly be challenged if certain capabilities of such anelectronic apparatus happens to be available to wrong hands.

Different solutions using passwords, and possibly added with encryption,exist today, but the ability to remember passwords, and the requirementto remember a lot of them, many times make the choice of passwords poor,or that the passwords are noted and many times in an insecure place. Thesecurity of such solutions is thus limited.

Electronic devices present today devoid of input mechanisms capable ofproviding alternative means of authentication and input. It may not bedesirable to add all such means to all devices due to e.g. size, costand/or battery consumption.

SUMMARY

An object of the invention is to at least alleviate the above statedproblem. The present invention is based on the understanding that theneed exists for an accessory such that input for multifactorauthentication exists in the form of human fingerprint biometrics andsmart card tokens. Whereas one or more input elements may exist withinthe accessory to provide alternate forms of input, authentication,validation, or actions to software operating on or within the electronicdevice.

According to a first aspect, there is provided an apparatus forattaching to an electronic device, where the electronic device comprisesan electrical connector, a back side, a display arranged on a sideopposite to the back side, and lateral sides connecting the back sideand the side opposite to the back side. The apparatus comprises a firstbody comprising a back plane arranged to cover at least a part of thebackside of the electronic device when attached; an electrical connectorarranged to mate the electrical connector of the electronic device whenattached; a slot for insertion of a smartcard arranged at the back planepart, the slot comprising electrical contacts for connecting to thesmartcard when inserted; a fingerprint reader; and circuitry connectedto the electrical connector, the electrical contacts and the fingerprintreader. The first body comprises a part that is arranged to abut to atleast one of the lateral sides of the electronic device when attached.The apparatus further comprises a support arranged to keep the apparatusfixed to the electronic device when attached by abutting at least onefurther lateral side of the electronic device when attached.

The apparatus may further comprise a second body arranged to mate withthe first body when attaching to the electronic device, wherein thesecond body comprises the support. The first body may be arranged toslide onto the electronic device from a lateral side thereof, and thesecond body may comprise a back plane and may be arranged to slide ontothe electronic device from an opposite lateral side thereof, and thefirst and second bodies may be arranged to snap lock at a position ofmating of the back planes of the first and second bodies. The secondbody may comprise a slot for insertion of a smartcard arranged at theback plane thereof such that, when attached to the electronic device,the slots of the back planes of the first and second body form the slotfor insertion of the smartcard, and wherein at least a part of the backplane of the second body may be transparent such that printedinformation of the smartcard is visible through the back plane of thesecond body when the smartcard is inserted. The back plane of the firstbody may comprise a surface essentially transversal to the slidingdirection and a surface essentially longitudinal to the slidingdirection, and the back plane of the second body may comprise a surfaceessentially transversal to the sliding direction and a surfaceessentially longitudinal to the sliding direction such that therespective transversal and longitudinal surfaces mate when attached toalign the first and second bodies when attached to the electronicdevice.

The back plane of the second body may comprise a recess or cavity at anouter part thereof such that the smart card, when inserted, isaccessible to be removed.

The first body may be arranged onto the electronic device, and thesecond body may comprise lateral sides and may be arranged to slide ontothe electronic device such that the second body encases at least onelateral side of the electronic device and at least one lateral side ofthe first body, and the first and second bodies may be arranged tomutually snap lock.

The first body may comprise the support, and the back plane mayresilient such that when attaching the apparatus to the electronicdevice, the support and the part abuts at least two opposite lateralsides of the electronic device. Thereby, a single-body solution isenabled. The slot for insertion of the smartcard may be a groovearranged on a side of the back plane proximal to the electronic devicewhen attached such that the smartcard is kept in place by the groove andthe electronic device when attached.

The fingerprint reader may be a line sensor arranged to read afingerprint upon sliding a finger over the sensor and sequentiallyreading a plurality of images thereof. The apparatus may furthercomprise a guide protrusion or guide groove arranged to provide atactile direction indicator transversal to the elongation of the linesensor.

The fingerprint reader may be arranged to read a fingerprint from afinger held still against the reader during reading. The apparatus mayfurther comprise a guide protrusion or groove arranged to provide atactile indicator enabling the user to position the finger properly insense of position and/or direction to the reader.

The apparatus may further comprise one or more recess arranged toprovide access, when attached to the electronic device, for any of: acamera of the electronic device; a speaker of the electronic device; amicrophone of the electronic device; and a button of the electronicdevice.

Where the electronic device is arranged to, through its electricalconnector, detect an accessory by identifying on one or more of its pinsa short circuit to ground and/or a predefined resistance to ground, thecircuitry may further comprise a controllable impedance circuit arrangedto provide, to the one or more corresponding pins of the electricalconnector of the first body, short circuit and/or a predefinedresistance to ground corresponding to a selected mode of operation ofthe apparatus. The impedance circuit may comprise a first junction fieldeffect transistor, JFET, connected with its source to a groundpotential, its drain to a first one of the one or more pinscorresponding to accessory detection pins, and its gate connected to avoltage supply source of, or connectable to, the apparatus, via aresistor and the gate is further connected to a first control switch ofthe circuitry arranged to selectably short circuit the gate voltage to aground voltage, i.e. such that the voltage over gate-source is aboutzero. The impedance circuit may comprise a second junction field effecttransistor, JFET, connected with its source to a ground potential, itsdrain to a second one of the one or more pins corresponding to accessorydetection pins via a resistor of a predefined size, and its gateconnected to a voltage supply source of, or connectable to, theapparatus, via a resistor and the gate is further connected to a secondcontrol switch of the circuitry arranged to selectably short circuit thegate voltage to a ground voltage, i.e. such that the voltage overgate-source is about zero.

The apparatus may further comprise a Universal Serial Bus, USB,connector arranged to enable connection to a USB host, wherein the USBconnector is connected to the circuitry. The voltage supply source maybe provided through the USB connector.

The circuitry may be controlled by a processor on which ahardware-interfacing software is executed for performing the control,and upon the electronic device being arranged to interact with theapparatus under control of an executed application, any update of thehardware-interfacing software is provided through an update of theapplication of the electronic device.

The circuitry may be arranged for extracting features from a fingerprintimage read by the fingerprint reader.

According to a second aspect, there is provides a combined devicecomprising an electronic device comprising an electrical connector, aback side, a display arranged on a side opposite to the back side, andlateral sides connecting the back side and the side opposite to the backside; and an apparatus according to the first aspect.

Other objectives, features and advantages of the present invention willappear from the following detailed disclosure, from the attacheddependent claims as well as from the drawings. Generally, all terms usedin the claims are to be interpreted according to their ordinary meaningin the technical field, unless explicitly defined otherwise herein. Allreferences to “a/an/the [element, device, component, means, step, etc]”are to be interpreted openly as referring to at least one instance ofsaid element, device, component, means, step, etc., unless explicitlystated otherwise. The steps of any method disclosed herein do not haveto be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of thepresent invention, will be better understood through the followingillustrative and non-limiting detailed description of preferredembodiments of the present invention, with reference to the appendeddrawings.

FIG. 1 illustrates an apparatus according to an embodiment attached withan electronic device.

FIG. 2 schematically illustrates insertion of a smart card into anapparatus according to an embodiment.

FIG. 3 illustrates views of a body of an apparatus according to anembodiment.

FIG. 4 illustrates views of another body of the apparatus according tothe embodiment of FIG. 3.

FIG. 5 schematically illustrates assembly of an apparatus according toan embodiment with an electronic device.

FIG. 6 schematically illustrates insertion of a smart card into anapparatus according to an embodiment.

FIG. 7 schematically illustrates an apparatus as of FIG. 6 with thesmart card inserted.

FIG. 8 illustrates views of mated bodies of an apparatus according to anembodiment.

FIG. 9 illustrates perspective views of mated bodies of an apparatusaccording to an embodiment.

FIG. 10 illustrates an apparatus according to an embodiment.

FIG. 11 illustrates insertion of a smart card into an apparatus as ofFIG. 10.

FIG. 12 illustrates an apparatus according to an embodiment.

FIG. 13 illustrates assembly of an apparatus according to an embodimentwith an electronic apparatus.

FIG. 14 illustrates a fingerprint reader according to an embodiment.

FIG. 15 is a schematic circuit diagram illustrating an embodiment.

FIG. 16 is a schematic circuit diagram illustrating an embodiment.

DETAILED DESCRIPTION

FIGS. 1 and 2 schematically illustrate the obverse and reverse views ofan apparatus 100 for attaching to an electronic device 102, which isshown in attached position. A suitable electronic device 102 isillustrated in detached position in FIGS. 5 and 13. The electronicdevice 102 comprises (reference numerals depicted in FIG. 13) anelectrical connector 103, a back side 105, a display 107 arranged on aside 109 opposite to the back side 105, and lateral sides 111, 113, 115,117 connecting the back side 105 and the side 109 opposite to the backside 105, which is a construction that is fairly popular among devicessuch as mobile phones, communicators, smartphones, personal digitalassistants, and the like.

The apparatus 100 comprises a back plane 104 arranged to cover at leasta part of the backside 105 of the electronic device 102 when attached.The back plane 104 is arranged to provide a part of the support forforming the usable combination of the apparatus 100 and the electronicdevice 102, which thus forms a combined device providing enhancedfeatures compared to the electronic device 102 alone. The back plane 104further provides the function of having a slot 106 for insertion of asmartcard 108. The size and position of the backplane 104 makes itparticularly suitable for this. Inside the slot, electrical contacts(not visible in FIGS. 1 and 2) for connecting to the correspondingcontacts 110 of the smartcard 108, when inserted, are provided. Further,an electrical connector 112 (not visible in FIGS. 1 and 2; referencenumeral depicted in FIG. 4) of the apparatus 100 is arranged to mate theelectrical connector 103 of the electronic device when attached.

The apparatus 100 also comprises fingerprint reader 114. The fingerprintreader 114, together with its associated algorithms foridentification/authentication and security functions for access to dataand/or applications/functions of the electronic device provides for theenhanced functionality of the combined device referred to above.

The apparatus 100 further comprises circuitry connected to theelectrical connector 112, the electrical contacts and the fingerprintreader 114. The circuitry is preferably controlled by a processorthereof on which a hardware-interfacing software, commonly calledfirmware, is executed for performing the control. The algorithmsassociated with the fingerprint reader, referenced to above, may beperformed at least partly by the circuitry. Here, it is to be noted thatsuch algorithms are normally a joint effort by the circuitry, theattached electronic device 102 and an inserted smartcard 108, and howthese efforts are divided between them is a choice of design, and mayfor example depend on the demands of the functionality, availableprocessing power in respect of the three entities, and desired degree ofversatility. The circuitry is for example particularly suitable fortaking care of feature extraction from read fingerprints. Related to thetopic of cooperation between these entities, a particularly suitable usecase is to be mentioned. In this use case, the electronic device isarranged to interact with the apparatus under control of an executedapplication. This can be a downloaded application which comprises theexecutable code which enables the electronic device 102 to perform acertain task. The apparatus 100, which may be mandatory for performingthat particular task, and/or for being able to use the application, maybenefit from the mechanism of such downloadable applications. Suchapplications are commonly provided with updates, which the electronicdevice downloads from time to time. Upon any update of the firmware ofthe apparatus, that update is provided through an update of theapplication of the electronic device, e.g. the firmware is appended toan update of the application, and is then provided to the apparatus 100when attached. Thereby, no complex mechanism or infrastructure for theupdate of the firmware of the apparatus 100 is needed.

To provide a usable combined device as referred to above, it isdesirable that the mechanical fit is such that when attached, thecombined device is kept securely together, while if the electronicdevice is to be detached, that should be rather simple and certainlywithout demands for certain tools. This is achieved by the apparatus 100having a part that is arranged to abut to at least one of the lateralsides of the electronic device when attached. This part is preferablyalso the part where the electrical connectors of the electronic device102 and the apparatus 100 mates. The apparatus then also comprises ansupport arranged to keep the apparatus fixed to the electronic devicewhen attached by abutting at least one further lateral side of theelectronic device when attached. This is solved by some variants, whichare demonstrated below for a few representative embodiments.

FIGS. 3 and 4 illustrate an apparatus according to an embodiment, wherethe apparatus comprises two bodies 300, 302 which are arranged to mateto keep the electronic device to form the usable combined device, whichis illustrated in FIG. 5. FIG. 4 illustrates a first body 300 and FIG. 3illustrates a second body 302, which bodies are arranged to mate. Bothin FIG. 3 and FIG. 4, the respective body 300, 302 are illustrated inorthographic views which together show all sides of the respectivebodies 300, 302.

The first body 300 comprises a back plane 304 arranged to cover at leasta part of the backside of the electronic device when attached, theelectrical connector 112 arranged to mate the electrical connector ofthe electronic device when attached, a slot 306 for insertion of thesmartcard arranged at the back plane part and comprising the electricalcontacts for connecting to the smartcard when inserted. The first body300 also comprises the fingerprint reader 308, and the circuitry whichis connected to the electrical connector, the electrical contacts andthe fingerprint reader. The first body 300 comprises a part 310 that isarranged to abut to at least one of the lateral sides of the electronicdevice when attached, which here can be seen to be arranged to abut thewhole of one of the lateral sides, and parts of two other lateral sidesof an electronic device.

The second body 302, which is arranged to mate with the first body 300when attaching to the electronic device, can here be seen to comprise asurface 312 for abutting at least one further lateral side of theelectronic device when attached, i.e. the opposite lateral side to theone abutted entirely by the first body 300, and also parts of two otherlateral sides of the electronic device. Thus, in this embodiment alllateral sides of the electronic device will be encased by the first andsecond bodies when attached. Attaching can be performed for example bysliding the first body onto the electronic device from a lateral sidethereof, and sliding the second body onto the electronic device from anopposite lateral side thereof, and the first and second bodies can snaplock at a position of mating of the back planes of the first and secondbodies 300, 302, by corresponding means, here illustrate as a protrusion314 with a recess or cavity 316 of the second body 302 which is arrangedto correspond to a protrusion 318 of the first body 300 arranged to snapinto the recess or cavity 316 since the protrusion 314 is slightlyresilient. The arrangement of protrusions and recesses or cavities canof course be arranged such that the elements 314, 316 are arranged onthe first body and the element 318 is arranged on the second body.Further, the protrusion 318 can be substituted by a recess or cavity ifthe recess or cavity 316 is substituted by a protrusion in any of thestructures demonstrated above.

The second body 302 comprises a slot 320 for insertion of the smartcardarranged at the back plane 319 thereof such that, when attached to theelectronic device, the slots 306, 320 of the back planes 304, 319 of thefirst and second bodies 300, 302 form the slot for insertion of thesmartcard. The whole or at least a part of the back plane 319 of thesecond body 302 is transparent such that printed information of thesmartcard is visible through the back plane 319 of the second body 302when the smartcard is inserted, as is illustrated by FIGS. 6 and 7.

The back plane of the first body 304 can comprise at least one surface322 essentially transversal to the sliding direction of mounting and asurface essentially longitudinal to the sliding direction of mounting.The back plane of the second body 302 can comprise at least one surface324 essentially transversal to the sliding direction and at least onesurface essentially longitudinal to the sliding direction such that therespective transversal and longitudinal surfaces 322, 324 mate whenattached to align the first and second bodies when attached to theelectronic device; this will provide aligned fit and stability to thecombined device.

The back plane of the second body 302 can comprise a recess 326 at anouter part thereof such that the smart card, when inserted, isaccessible to be removed. A bulge 328 provided on the second body 302can be provided to keep the smart card in place when inserted.

The first body 304 can be arranged to slide onto the electronic device,such that the electrical connector 112 mates with a correspondingconnector of the electronic device. The first body 304 can compriselateral sides 330. The second body 302 can comprise lateral sides 332and be arranged to slide onto the electronic device from the other sidethereof such that the second body 302 encases at least one lateral sideof the electronic device by the lateral sides 332 and at least onelateral side 330 of the first body 304 encases at least one lateral sideof the electronic device, and the first and second bodies are arrangedto mutually snap lock, e.g. by elements 314, 316 and 318.

FIG. 5 illustrates mounting the first and second bodies on an electronicdevice to form a single functional unit. FIG. 6 illustrates insertion ofa smart card into the functional unit, wherein FIG. 7 illustrates thefunctional unit with the smart card inserted. FIG. 7 also illustrates,depicted by dotted lines, the contacts of the smart card, in realityhidden inside the card slot, to indicate the position of correspondingcontacts of the first body to mate with the contacts of the smart card.FIGS. 8 and 9 illustrate a first and a second body 802, 804 mated, butwithout the electronic device being involved. The illustrations areshown to depict both how surfaces 806, 807, 808, 809, 810, 811 of thefirst and second bodies 802, 804 mate, and how a variant of the cardslot 812 and mating surfaces can be arranged. FIGS. 8 and 9 also depictsthat cavities for accessing keys or buttons of the electronic apparatuscan be substituted by keys or buttons 814 arranged to mechanicallyinteract with keys or buttons of the apparatus.

FIGS. 10 and 11 illustrate a single body solution. A single body 1000comprises similar functionality as demonstrated for the two-bodysolution, but the mechanical properties are somehow different, as willbe demonstrated here. The single body 1000 comprises circuitry connectedto an electrical connector 1001 arranged to mate a correspondingconnector at the electronic device, a smart card reader, preferablyarranged as a card slot 1003 but may be arranged for example asillustrated in FIG. 12, comprising electrical contacts arranged to matecontacts of a smart card and a fingerprint reader 1005. A back plane1002 of the single body 1000 is resilient such that when attaching theapparatus to the electronic device, a part 1004 having the electricalconnector 1001 and a support 1006 arranged to face an opposite lateralside of the electronic device abuts at least two opposite lateral sidesof the electronic device. The electronic device is thus at least partlyencased on its lateral sides such that it is kept in place. By theresilient back plane 1002, the single body is wrapped onto theelectronic device.

FIGS. 12 and 13 illustrates an alternative solution. A body 1200comprises circuitry connected to an electrical connector 1201 arrangedto mate a corresponding connector at the electronic device, a smart cardreader 1208, comprising electrical contacts 1210 arranged to matecontacts of a smart card, and a fingerprint reader 1205. A part 1204having the electrical connector 1201 is arranged to face a lateral sideof the electronic device. A back plane 1202 is rigid and a frame 1205 isarranged to be attached around the part 1204 and the electronic devicewhen it is attached, wherein a lock mechanism 1206 which is arranged tolock with the frame 1212 when it is attached. The lock may be releasedby actuating an unlock key or lever. The smart card reader 1208 cancomprise a groove 1214 arranged on a side of the back plane proximal tothe electronic device when attached such that the smartcard is kept inplace by the groove and the electronic device when attached. Atransparent part 1216 of the back plane 1202 can enable visualinformation on the smart card from outside when the functional unit isassembled.

In the embodiments demonstrated above, the fingerprint reader can be aline sensor, as depicted in FIGS. 1, 4, 5, 8, 9. 10, 12 and 13, arrangedto read a fingerprint upon sliding a finger over the sensor andsequentially reading a plurality of images thereof. The apparatus canfurther comprise a finger guide protrusion or guide groove arranged toprovide a tactile direction indicator transversal to the elongation ofthe line sensor, as depicted in FIGS. 1, 4, 5, 8, 9, 10 and 12. Theapparatus can also be provided without such direction indicator, asdepicted in FIG. 13. The tactile guide can for example be arrangedcentred along the elongation of the line sensor.

Alternatively, the fingerprint reader is arranged to read a fingerprintfrom a finger held still against the reader during reading, which isoften referred to as a flat bed sensor and an image or representation ofa major part of a fingertip, where the fingerprint information ispresent is present, is read. For consistent positioning of the finger,such that the read fingerprint image or representation is fairly easy tocompare with a stored template of the fingerprint, the apparatus canfurther comprises a guide protrusion or groove arranged to provide atactile indicator enabling the user to position the finger properly insense of position and/or direction to the reader. An example of suchfingerprint reader is depicted in FIG. 14, where the fingerprint reader1400 is arranged on the electronic apparatus 1402. The fingerprintreader 1400 has its sensor surface 1404 where the major part of thefingertip is to be arranged at reading. The finger positioning is inthis example aided both by a groove 1406 arranged around the sensor, andbulges 1408, 1409 arranged such that they can be, by tactile recognitionby the finger applied, felt and the finger is easily enabled to be putin the right position and direction by the user. The example depicted inFIG. 14 is applicable to any of the embodiments demonstrated herein asan alternative to the otherwise depicted line sensor. The apparatus canalso be provided with such flat bed sensor without such direction orposition indicator. The apparatus can further comprise one or moreextrusions arranged to provide access, when attached to the electronicdevice, for any of:

-   -   a camera of the electronic device, as illustrated by reference        numeral 150 in FIG. 2;    -   a speaker of the electronic device, as illustrated by reference        numeral 350 in FIG. 3;    -   a microphone of the electronic device, as illustrated by        reference numeral 450 in FIG. 4; and    -   a button of the electronic device, as illustrated by reference        numeral 950 in FIG. 9.

The electronic device, e.g. a smartphone, can be arranged to, throughits electrical connector to the apparatus, detect an accessory, e.g. theapparatus, by identifying on one or more of its pins a short circuit toground and/or a predefined resistance to ground. This can be used byarranging the circuitry of the apparatus to further comprise,illustrated in FIGS. 15 and 16, a controllable impedance circuit 1500,1600 arranged to provide, to the one or more corresponding pins of theelectrical connector, short circuit to ground and/or a predefinedresistance corresponding to a selected mode of operation of theapparatus. Thereby will the electronic device be able to detectattachment to the apparatus and/or adapt its mode of operationaccordingly.

The impedance circuit 1500 can comprise a first junction field effecttransistor, JFET, 1502 connected with its source to a ground potential,its drain to the of the one or more pins corresponding to accessorydetection pins, and its gate connected to a resistor to a voltage supplysource of, or connectable to, the apparatus, and the gate is furtherconnected to a first control switch 1504 of the circuitry arranged toselectably, by closing the switch 1504, pull the gate voltage towards aground voltage, i.e. short circuit gate to ground such that the voltageover gate-source becomes about zero, wherein the accessory pin willexperience that nothing is connected thereto. When the apparatus isconnected to the electronic device, i.e. there is a supply voltageapplied, and the switch is open, the JFET 1502 will disconnect theaccessory pin from ground since the supply voltage applied to the gatewill pinch the JFET 1502 since gate-source voltage becomes about thesupply voltage, and the electronic device will consider the situation asno accessory is connected, while if the apparatus is not connected to asupply voltage, the gate voltage is the same as the source voltage, e.g.grounded through discharge resistor R₂, wherein the JFET 1502 isconducting through drain-source, and the pin is in a state where it isenabled to detect the apparatus as a connected accessory. This enablesvirtual disconnection/connection of the accessory, i.e. the apparatus,which can be used for situations such as changing role, i.e. operationmode, of the apparatus. An example of this is provided below for USBconnection where the supply voltage is provided by the USB connection.An advantage of the demonstrated JFET circuit 1500 is that the JFET willbe in conductive state when no voltage is provided to the gate. That is,the circuit will work although not being powered at connection.

The impedance circuit 1600 can comprise a second junction field effecttransistor, JFET, 1602 connected with its source to a ground potential,its drain to another one of the one or more pins corresponding toaccessory detection pins, e.g. accessory identity (ID) pin, via aresistor R_(ID) of a predefined size, and its gate connected to aresistor R₁ further connected to a second control switch 1604 of thecircuitry arranged to selectably short circuit the gate voltage to aground voltage, i.e. such that voltage over gate-source is about zero.The function of the second JFET 1602 and the second switch 1604 issimilar to what has been demonstrated for JFET 1502 and switch 1504 ofFIG. 15.

In the embodiments of the impedance circuit demonstrated above, itshould be understood that they can be used in combination or sole. Inthe circuits demonstrated with reference to FIGS. 15 and 16, there isoptionally provided a discharge resistor R₂ which is arranged todischarge any capacitors present or inherent in the circuitry when theapparatus is disconnected from the electronic apparatus such that thegate voltage falls sufficiently quick upon disconnection. The resistorR₂ is thus selected based on such present capacitances and the demandfor fall time for the gate voltage.

The apparatus can comprise a Universal Serial Bus, USB, connectorarranged to enable connection to a USB host, wherein the USB connectoris connected to the circuitry, wherein the voltage supply source isprovided through the USB connector. The voltage supplied through the USBconnector can thus, by the circuitry and its JFET connectionautomatically enable switching mode of the electronic device. FIG. 15schematically illustrates the principles of such circuitry. The USBconnection provides, through its V_(bus) pin, a supply voltage of about5V when connected, which is provided through the resistor R₁. Thevoltage of the supply is provided to the gate of a JFET 1502. The drainterminal of the JFET 1502 is connected to an accessory detect pin of theconnector, and thus to the connected electronic device. The JFET 1502 isthus forced into a state where no connection between drain and source isprovided, and the accessory, i.e. the apparatus is virtuallydisconnected. By closing the switch 1504, virtual reconnection can bemade.

The nature of the JFET 1502, 1602, which is of p-channel type, is thatthe channel is pinched, i.e. there is no electrical connection betweenits drain and source, if the voltage between its gate and source is highenough, say a few volts. When the switch 1504, 1604 connected to thegate terminal is open, the voltage at the gate terminal is defined bythe voltage supplied, and the voltage at the source terminal is zerosince it is connected to ground. By the short circuit, achieved throughthe switch 1504, 1605, of the gate to same potential as the source, thechannel is pinched when the switch is closed. The effect is that theelectronic device will detect that no accessory is connected since thereis no connection between drain and source of the JFET 1502, 1602 andthus no connection from the accessory pin to a reference voltage, i.e.ground, and the mode is set to operate as no accessory is present whenthe USB is connected. This can be used for enabling the USB to operatewith the electronic device without interference with the accessory, i.e.the apparatus, or that the apparatus after a while, when for examplesome handshake procedure is set, closes the switch 1504, i.e. undercontrol of the circuitry of the apparatus, which will make theelectronic device detect the accessory and change mode of operationaccordingly. The latter is found to be a desired way of changing modefrom “accessory connected” to “USB connected”. This can also be used forchanging mode of operation of the apparatus, wherein another resistanceR_(ID) is applied, as will be further demonstrated below, for indicatingthat to the electronic device. A similar virtualdisconnection/reconnection can be used to achieve the switch of mode ofoperation.

FIG. 16 illustrates a similar circuit, but here connected to anaccessory identification, ID, pin. The electronic apparatus can bearranged to detect different types of accessories depending on theamount of resistance to ground detected at accessory ID pin. Theapparatus is then able to choose to connect a certain identificationresistance R_(ID) to the ID pin to identify itself, or to identify thepresent role the apparatus intends to work in. There can thus be severalsuch circuits, one for each role, which can be selectively connected tothe ID pin.

The use of a p-channel JFET this way, with its source grounded insteadof the more common application where the source is connected to a supplyvoltage and drain is connected to ground via a resistor, wherein theoutput is achieved over the resistor, enables a circuitry with very fewcomponents, robust behaviour, and versatility to be applicable forconnecting the apparatus to most electronic devices. The robustbehaviour is implied by the circuit enabling the full supply voltage tobe applied over gate-source, and no voltages above supply voltage, as ife.g. a traditional connection of a p-channel JFET was used, or negativevoltages, as if e.g. an n-channel JFET was used, are needed to becreated. The versatility becomes inherent by the fact that there iscommonly a supply voltage available, and the simpledetection/identification by the electronic device sensing of groundedand/or resistances to ground is commonly used. For making the circuitryversatile for several devices utilising different resistance values, abank of such impedance circuits can be provided and the applicableimpedance circuits are enabled by controlling the respective switchesamong them. This will further enhance production of circuits for aseries of products, i.e. apparatuses, dedicated to different electronicapparatuses, where the same circuitry can be used for all the products.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope of the invention, as defined by the appendedpatent claims.

The invention claimed is:
 1. An apparatus for attaching to an electronicdevice, the electronic device comprising an electrical connector, a backside, a display arranged on a side opposite to the back side, andlateral sides connecting the back side and the side opposite to the backside, the apparatus comprising a first body comprising a back planearranged to cover at least a part of the backside of the electronicdevice when attached; an electrical connector arranged to mate theelectrical connector of the electronic device when attached; a slot forinsertion of a smartcard arranged at the back plane part, the slotcomprising electrical contacts for connecting to the smartcard wheninserted; a fingerprint reader; and circuitry connected to theelectrical connector, the electrical contacts and the fingerprintreader, wherein the first body comprises a part that is arranged to abutto at least one of the lateral sides of the electronic device whenattached, the apparatus further comprising a support arranged to keepthe apparatus fixed to the electronic device when attached by abuttingat least one further lateral side of the electronic device whenattached; a second body arranged to mate with the first body whenattaching to the electronic device, wherein the second body comprisesthe support wherein the first body is arranged to be slid onto theelectronic device from a lateral side thereof, and the second bodycomprises a back plane and is arranged to be slid onto the electronicdevice from an opposite lateral side thereof, and the first and secondbodies are arranged to snap lock at a position of mating of the backplanes of the first and second bodies, and wherein the second bodycomprises a slot for insertion of a smartcard arranged at the back planethereof such that, when attached to the electronic device, the slots ofthe back planes of the first and second body form the slot for insertionof the smartcard, and wherein at least a part of the back plane of thesecond body is transparent such that printed information of thesmartcard is visible through the back plane of the second body when thesmartcard is inserted.
 2. The apparatus according to claim 1, whereinthe back plane of the first body comprises a surface essentiallytransversal to the sliding direction and a surface essentiallylongitudinal to the sliding direction, and the back plane of the secondbody comprises a surface essentially transversal to the slidingdirection and a surface essentially longitudinal to the slidingdirection such that the respective transversal and longitudinal surfacesmate when attached to align the first and second bodies when attached tothe electronic device.
 3. The apparatus according to claim 1, whereinthe first body is arranged onto the electronic device, and the secondbody comprises lateral sides and is arranged to slide onto theelectronic device such that the second body encases at least one lateralside of the electronic device and at least one lateral side of the firstbody, and the first and second bodies are arranged to mutually snaplock.
 4. The apparatus according to claim 1, wherein the first bodycomprises the support, and the back plane is resilient such that whenattaching the apparatus to the electronic device, the support and thepart abuts at least two opposite lateral sides of the electronic device.5. The apparatus according to claim 4, wherein the slot for insertion ofthe smartcard is a groove arranged on a side of the back plane proximalto the electronic device when attached such that the smartcard is keptin place by the groove and the electronic device when attached.
 6. Theapparatus according to claim 1, wherein the fingerprint reader is a linesensor arranged to read a fingerprint upon sliding a finger over thesensor and sequentially reading a plurality of images thereof, and theapparatus further comprising a guide protrusion or guide groove arrangedto provide a tactile direction indicator transversal to the elongationof the line sensor.
 7. The apparatus according to claim 1, wherein thefingerprint reader is arranged to read a fingerprint from a finger heldstill against the reader during reading, and the apparatus furthercomprising a guide protrusion or groove arranged to provide a tactileindicator enabling the user to position the finger properly in sense ofposition and/or direction to the reader.
 8. The apparatus according toclaim 1, further comprising one or more recess arranged to provideaccess, when attached to the electronic device, for any of: a camera ofthe electronic device; a speaker of the electronic device; a microphoneof the electronic device; and a button of the electronic device.
 9. Theapparatus according to claim 1, further comprising a Universal SerialBus, USB, connector arranged to enable connection to a USB host, whereinthe USB connector is connected to the circuitry connected to theelectrical connector.
 10. The apparatus according to claim 1, whereinthe circuitry connected to the electrical connector is controlled by aprocessor on which a hardware-interfacing software is executed forperforming the control, and upon the electronic device being arranged tointeract with the apparatus under control of an executed application,any update of the hardware-interfacing software is provided through anupdate of the application of the electronic device.
 11. The apparatusaccording to claim 1, wherein the circuitry connected to the electricalconnector is arranged for extracting features from a fingerprint imageread by the fingerprint reader.
 12. An apparatus for attaching to anelectronic device, the electronic device comprising an electricalconnector, a back side, a display arranged on a side opposite to theback side, and lateral sides connecting the back side and the sideopposite to the back side, the apparatus comprising a first bodycomprising a back plane arranged to cover at least a part of thebackside of the electronic device when attached; an electrical connectorarranged to mate the electrical connector of the electronic device whenattached; a slot for insertion of a smartcard arranged at the back planepart, the slot comprising electrical contacts for connecting to thesmartcard when inserted; a fingerprint reader; and circuitry connectedto the electrical connector, the electrical contacts and the fingerprintreader, wherein the first body comprises a part that is arranged to abutto at least one of the lateral sides of the electronic device whenattached, the apparatus further comprising a support arranged to keepthe apparatus fixed to the electronic device when attached by abuttingat least one further lateral side of the electronic device whenattached; a second body arranged to mate with the first body whenattaching to the electronic device, wherein the second body comprisesthe support wherein the first body is arranged to be slid onto theelectronic device from a lateral side thereof, and the second bodycomprises a back plane and is arranged to be slid onto the electronicdevice from an opposite lateral side thereof, and the first and secondbodies are arranged to snap lock at a position of mating of the backplanes of the first and second bodies, and wherein the back plane of thesecond body comprises a recess or cavity at an outer part thereof suchthat the smart card, when inserted, is accessible to be removed.
 13. Anapparatus for attaching to an electronic device, the electronic devicecomprising an electrical connector, a back side, a display arranged on aside opposite to the back side, and lateral sides connecting the backside and the side opposite to the back side, the apparatus comprising afirst body comprising a back plane arranged to cover at least a part ofthe backside of the electronic device when attached; an electricalconnector arranged to mate the electrical connector of the electronicdevice when attached; a slot for insertion of a smartcard arranged atthe back plane part, the slot comprising electrical contacts forconnecting to the smartcard when inserted; a fingerprint reader; andcircuitry connected to the electrical connector, the electrical contactsand the fingerprint reader, wherein the first body comprises a part thatis arranged to abut to at least one of the lateral sides of theelectronic device when attached, the apparatus further comprising asupport arranged to keep the apparatus fixed to the electronic devicewhen attached by abutting at least one further lateral side of theelectronic device when attached; a second body arranged to mate with thefirst body when attaching to the electronic device, wherein the secondbody comprises the support wherein the first body is arranged to be slidonto the electronic device from a lateral side thereof, and the secondbody comprises a back plane and is arranged to be slid onto theelectronic device from an opposite lateral side thereof, and the firstand second bodies are arranged to snap lock at a position of mating ofthe back planes of the first and second bodies, and wherein theelectronic device is arranged to, through its electrical connector,detect an accessory by identifying on one or more of its pins a shortcircuit to ground and/or a predefined resistance to ground, thecircuitry further comprising a controllable impedance circuit arrangedto provide, to the one or more corresponding pins of the electricalconnector of the first body, short circuit and/or a predefinedresistance to ground corresponding to a selected mode of operation ofthe apparatus.
 14. The apparatus according to claim 13, wherein theimpedance circuit comprises a first junction field effect transistor,JFET, connected with its source to a ground potential, its drain to afirst one of the one or more pins corresponding to accessory detectionpins, and its gate connected to a voltage supply source of, orconnectable to, the apparatus, via a resistor and the gate is furtherconnected to a first control switch of the circuitry arranged toselectably short circuit the gate voltage to a ground voltage.
 15. Theapparatus according to claim 14, further comprising a Universal SerialBus, USB, connector arranged to enable connection to a USB host, whereinthe USB connector is connected to the circuitry, wherein the voltagesupply source is provided through the USB connector.
 16. The apparatusaccording to claim 13, wherein the impedance circuit comprises a secondjunction field effect transistor, JFET, connected with its source to aground potential, its drain to a second one of the one or more pinscorresponding to accessory detection pins via a resistor of a predefinedsize, and its gate connected to a voltage supply source of, orconnectable to, the apparatus, via a resistor and the gate is furtherconnected to a second control switch of the circuitry arranged toselectably short circuit the gate voltage to a ground voltage.